Centrifugal breather



Sept. l2, 1939. R. cHlLToN GBNTRIFUGA'L BREATHER Filed April 8, 1936 2 Sheets-Sheet l INVENTOR. ROLAAL CHILTON BY l,

TTORNEY CENTRIFUGAL "BREATHER Y -Filed April 8. 1 9`s :sheets-sheet 2 INVENTORL 7d/SAND (HILTON ATTORNEY.

- Patented Sept. 12, 1939 UNITED Isii-.fires PATENTl ori-Ice mesne assignments,

to Wright 'Aeronautical Corporation, Paterson, N. J., a corporation of New York Application April s, 193s, serial No. '13,191

1a claims.

This invention relates to breathing and lubricant scavenging for engine crankcases, and ,com-

prises means correlating these two functions, whereby the normal breathing action is caused to assist scavenging of'excess oil from the crankcase. The invention is particularly applicable to I' internalcombustion engines of the dry sump type,

wherein oil is fed to the parts requiring lubrication in excessive quantities, and wherein the excess oil is withdrawn by a pump and delivered to a separate oil tank. In such engines it has been normalpracticeto employ a vent or breather open to the atmosphere to relieve rom the crankcase gases which collect therein as a result of escape past the engine-pistons. Dimculty has been experienced in eiecting a thorough hseparation of gas from oil atomized by the rapidly moving engine parts, which normally whip the oil into a 20 fine mist or froth, this 'mist having a density not widely different from that of the crankcase gases. Engines are usually provided with a sump into which excess oil drains for scavenging, but ordiv narily, a substantial amount of oil is lost through 25 the breather despite breather location, and baffles or screens which may be associated therewith to prevent oil loss.' located in a high and relatively quiet and nonturbulent part of the `crankcase, there is a sub- 30 stantial oil loss therethrough resulting in oil deposition on the outside of the engine with consequent dirtiness and .undue oil consumption. If ventilation is resorted to wherein the oil carrying mist is diverted to thecengine intake, undue oill to provide a centrifugal separator 'to remove oil" particles from crankcase gases,. Afurther object is to augment the scavenging of oil from a crank-A case by utilizing the common tendency for the oil 5 mist to pass toward a breather opening, in locating the breather opening for the crankcase adjacent the oil sump. This reduces the normal diffusion of the oil carrying crankcase` vapors, concentrating them at locations where separati/on of the oilmay be aiected by gravity, or by a centrifuge, or by both. l

I have chosen for an illustrative embodiment of the invention, the crankcase of a radial cylinder 'aircraft engine, shownin the annexed drawings, in which:

Even when the breather is Fig. 1 isa fragmentary view through an engine crankcase embodying the invention; and

Fig. 2 is an enlarged view of a portion of Fig. 1.

A main crankcase section l0 is provided with a. front section i2 defining a forward compartment 5 and a rear section. I4 dening a rear compartment.' The various cylinders and parts subject .to motion are not shown since they form no part of the invention. Sumce -it to say, however, thatA the front, central and rear compartments, in en- 10 gine operation, are 4filled vwith oil spray and mist, and'that a certain amount of gas enters the compartments 'from the engine cylinders whichmust be disposed of by a breather opening. -At the lower part of the end. partitions of the section 15 Ill, openings i6 and i8 are provided to permit of compartment intercommunication. Thus oil may flow from any compartment through connections and 22 to an oil sump 24 carried by said connections. 1

I form a breather opening 26. in the sump 24, forming the entrance to 'a conduit 28 entering the)top of an oil reservoir 30. From a remote point on the top of the`oil' reservoir, a conduit 32 extends, which continues the breather passage and provides a vent for the oil tank. rIjhe structure thus far described in itself, comprises a sube stantial part of the invention. In operation oil laden crankcase gases will seek 'an outletl which necessarily is the opening 26. A substantial amount of oil particles will deposit in the sump, -the flow of gases also augmenting the passage of larger particles of oil to the sump, whence the oil is delivere by a. conventional scavenge pump 33, from the ou 1ct 34 to the oil tank 30 by a pipe 35 35. The vapors pass through the conduit 28 to the tank 30, where more of the oil particles may Y settle, directly into the oil in the tank. 'I'he vent 32 then communicates with the atmosphere.

To provide for conditions where excessive tur- .10`

bulence in the crankcase has made the above described arrangement inadequate to effect complete separation of oil-from the crankcase gas, I provide a centrifuge shown in detail in Fig. 2. 'This comprises-a high speed engine driven shaft 45 36 journaled in upper part of the section I2. The driving means is not shown but conveniently comprises a conventional gear train. A member 38 ts over the shaft 36, forming a housing for an impeller 40 mounted on the shaft 33. The housing is formed with an eye portion 42 concentric with the impeller, communicating' with lan openr.y ing 44 to which the conduit 32 is connected. A drain opening 46, in the housing 38 and section I2, leads from a point adjacent vthe impeller periphery tothe front compartment Within the section I2. A baille 48 overlies the outer part of the irnpeller 48. Gases and oil particles entering the eye 42 are separated as they are picked up by the rotating irnpeller 40, the oil being thrown against the housing 38 and the gases passing radially inward to issue from the baille aperture 58 due to the low density of the gases alone.

I provide an outer housing 52 havingY a vent opening 54, the housing 52, with the baille 48 and the housing 38 being attached to the section l2 by studs 56.

A second irnpeller 58 may, if desired, be mounted on the shaft 36 on the outlet side of the baille 48, to augment gas passage through the centrifuge andto prevent a pressure drop thereacross, or to prevent a positive pressure being. built up in the crankcase by the first irnpeller 40.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover allsuch modifications and changes.

What is claimed is:

1. The combination with an engine crankcase having an oil sump and drainage passages for scavenging oil from said case into said sump, of a conduit terminating in an atmospheric vent connected to said sump, a centrifuge in said conduit adapted to separate oil particles from issuing vapor, and means to drain said separated oil back into the crankcase.

2. In an engine, in combination, a crankcase to be vented of vapors and scavenged of oil, an l atmospheric vent conduit connected to said crankcase through which said vapors and oil pass, a high speed irnpeller within said conduit adapted to centrifugally separate said oil from said vapor, and a connection whereby said separated oil is returned to said engine.

3. In an engine, in`combination, a crankcase to be vented of vapors and scavenged of oil, and having a scavenge passage, a tank into which scavenged oil iiows an atmospheric vent conduit 1 connecting to said tank at a point thereon re-' mote from said engine, an oil and vapor separating centrifuge in said conduit, and means to drain centrifuged oil back into said engine.

4. The combination with an engine, of an oil sump, an external oil tank, a rst ventpipe connecting said sump to said oil tank, a second vent pipe connecting said oil tank remotely of the rst said pipe to an` atmospheric vent, and oil separating means interposed in said second cjonnection. f

5. The combination of'an engine crankcase having-a sump, of an oil tank, a scavenging conof said tank forming the sole ventfor said crankcase, a vent for said tank an/dan oil separating centrifuge in said tank vent.

'7. The combination of an engine crankcase.

having an oil collecing sump`connected therebelow, of means to scavenge oil from said sump,

oil from said sump to said tank, a vent conduit v directly connecting said sump and tank, enter-` ing both said sump and tank at points above the normal liquid oil level thereof, and means for promoting vapor ow from said engine, through said vent conduit to said tank, comprising a blower organized to withdraw vapor from the tank.

9. In an engine casing containing oil vapor, a vent system for said casing comprising a. high speed.- irnpeller communicating at its eye with the interior of said casing, an oil collecting annulus encircling the irnpeller, said -annulus communicating with the casing interior for the return of collected oil to said casing, an air vent on the opposite side of said irnpeller from Asaid eye, and a booster irnpeller rotatable with the first irnpeller for discharging casing gases from said vent.

10. In combination, an engine crankcase havingan oil sump connected therebelow, means to scavenge oil from said sump, an engine driven centrifuge adapted to separate oil from vapor; a vapor conducting conduit leading from the upper part of said oil sump, above the normal liquid oil level, to the centrifuge intake; a duct leading from the centrifuge for discharging oil separated thereby into the engine crankcase, and a discharge duct on the centrifuge for gases from which oil has been separated. J

1l. In an internal combustion engine provided with a lubricating system wherein lubricant is delivered to theengine case, an oil sump below and having restricted communication with the case into which surplus liquid oil ilows, an oil tank separate from the engine, means for scavenging liquid oil from said sump and delivering same to said tank; a sole vent conduit for said engine directly connecting the upper part of said sump and the upper part of said tank, above the normal liquid oil level of both, wherefore crankcase gases and vapor under pressure within the case due to explosion leakage from the engine pass into said sump to promote liquid oil flow thereto before passing from the engine; and a breathing vent for said tank.

12. In an internal combustion engine provided with a lubricating system wherein lubricant is delivered to the engine case, an oil sump below and having restricted communication with the case into which surplus liquid oll ows, an oil tank separate from the engine, means for scavenging liquid oilfrom said sump and delivering same to said tank; a sole vent conduit for said engine directly connecting the upper part of said sump and the upper part of said tank, above the nor'- mal liquid oil level of lboth, wherefore crankcase gases and vapor under pressure within the case due to explosion leakage from the engine pass into said sump to promote liquid oil flow thereto before passing from the engine; and means to promote the exhaust of crankcase gases from the tank, which enter the tank from the engine case and sump.

13. 4In 'an internal combustion engine provided with a lubricating system wherein lubricant is delivered tothe`engine case, an oil sump below and having restricted communication with the case into which surplus liquid oil flows, an oil tank separate from the engine, means for scavenging liquid oil from said sump and delivering same to said tank, a sole vent conduit for said engine directly connecting the upper part of said sump and the upper part of said tank, above the 10 normal liquid gil level of both, wherefore crankcasegases and vapor under pressure Within the case due to explosion leakage from the engine pass into said sump to promote liquid oil ow thereto before passing from the engine; and breathing means for said tank comprising a device for separating residual oil particles from issuing vapor organized to discharge gases to the atmosphere and to return oil particles to.the 1ubrieating system.

ROLAND CHILTON. 10 

